Alch/Herb or Enchant/?Follow

Go Herb/Enchant.

Herb will bring in raw mats you can sell. Nice source on easy/constant money. You can buy whatever pots you need with money, and still have enough for all your training/mounts/etc...

Enchant - imho - is the most useful profession. It is a gathering/crafting profession all rolled into one. If you level this prof while leveling your toon, it will make you a ton of money.

With both of those professions, you will make a huge amount of money (much more than you main toon's professions). Plus, you'll save a ton of money since you won't ever have to buy dusts/essences/shards for enchants ever again.

That is my recommendation.

Enchanting will make you a ton of money, almost enough to not need a second gathering profession. However, a second gathering profession will make you even more money, since it's easy to gather while questing.

I prefer to buy potions direct from the AH rather than hoping someone online has the time/inclination to make what I want. Yes, it helps if you supply the materials for potions through your own herbalizing, but you still risk not having people on to help when you really want it, and usually need to tip anyway. It might save some money, but it wastes time. I'd rather take up mining; you make more early on, and a roughly equivalent amount late from what what I hear (although competition might be much worse). Then again, you've done mining already, so the choice is yours. You probably realize how much profit lies in Ore, though!

I'd go enchanting for sure, and mining as a second craft.

woot - I win! :) Just kidding.

The other nice thing about Herb is that there are a few things in Enchanting that use herbs. Oils for instance. They are useful for leveling skills, and buffing you/other people. I always make batches of Wizard and Mana Oil for raids.